Effect of different doses of monocrotaline in combination with isopropylarterenol on the hemodynamic response, heart index and right heart hypertrophy index in rats / 中国比较医学杂志

Objective To study the effect of different doses of monocrotaline in combination with isopropylarterenol on the hemodynamic resonse, heart index and right heart hypertrophy index in rats.Methods Sixty-four healthy adult SD rats, male:female=1∶1, body weight 200-250 g, were randomly divided into blank control group (n=16) and three model groups (n=16 in each group).The high dose model group (n=16) received i.p.injection of monocrotaline 80 mg/kg once and epinephrine 10 mg/kg once daily for one week.The moderate dose group received i.p. injection of monocrotaline 55 mg/kg once and epinephrine 8 mg/kg once daily for one week.The low dose group received i. p.injection of monocrotaline 30 mg/kg once and epinephrine 3 mg/kg once daily for one week.The rats were fed for 6 weeks, and then pulmonary artery pressure and right ventricular pressure were tested and heart index and right ventricular hypertrophy index were determined.Results Compared with the control group, the mean pulmonary artery pressure and right ventricular systolic blood pressure in the low dose monocrotaline group were not significantly changed, but significantly changed in the moderate dose monocrotaline group ( P<0.05) .The heart index and right ventricular hypertrophy index in the low dose monocrotaline group were not significantly changed, but in the moderate dose monocrotaline group, the heart index was significantly reduced ( P<0.01 ) and the right ventricular hypertrophy index was significantly increased ( P<0.05 ) .Conclusions The use of a single injection of 55 mg/kg monocrotaline in combination with continuous injection of 8 mg/kg isopropylarterenol once daily for one week can ensure the survival rate of rats, and the successful formation of pulmonary artery hypertension, leading to heart weakness.

Increased expression of nitric oxide synthases in left and right ventricular hypertrophy

The present study was aimed to explore pathophysiological implications of nitric oxide in the development of left and right ventricular hypertrophy. To induce selective left and right ventricular hypertrophy, rats were made two-kidney, one clip (2K1C) hypertensive and treated with monocrotaline (MCT), respectively. Six weeks later, the hearts were taken and their ventricular tissue mRNA and protein expression of endothelial constitutive isoform of nitric oxide synthase (NOS) were determined by reverse transcription-polymerase chain reaction and Western blot analysis, respectively. In 2K1C hypertensive rats, the expression of NOS mRNA was increased in parallel with its proteins in the left ventricle, but not in the right ventricle. In MCT-treated rats, the expression of NOS mRNA and proteins were proportionally increased in the right ventricle, but not in the left ventricle. These results suggest that the expression of NOS is specifically increased in association with the ventricular hypertrophy, which may be a mechanism counteracting the hypertrophy.

Left ventricular muscle mass regression after aortic valve replacement

Implanting a valve that will reduce left ventricular mass is critical in aortic stenosis. Regression of left ventricular hypertrophy in 46 aortic valve replacement (AVR) patients receiving a St. Jude Medical (SJM) valve was assessed by serial electrocardiographic and echocardiographic studies during the preoperative, immediate, and late postoperative periods. The patients were divided into three groups according to valve size; 19 mm group (n=9), 21 mm group (n=20), and 23+mm group (n=17). There was no surgical mortality. The NYHA functional class improved from an average of 2.2+/-0.8 preoperatively to 1.3+/-0.5 post-operatively. Left ventricular muscle mass index (LVMI) regression failed to reach statistical significance in the 19 mm group, whereas in the other two groups a steady decrease in the LVMI occurred with follow up. ECG findings were less remarkable showing insignificant differences in voltage among the three groups (p=0.000). In conclusion, the current data suggest that the 19 mm SJM valve may not result in satisfactory left ventricular muscle mass regression despite adequate function, even in small patients. Therefore, additional procedures to accommodate a larger valve may be warranted in the aortic annulus smaller than 21 mm.